Genetic diversity and inferred ancestry of Asian lotus(Nelumbo nucifera) germplasms in Thailand and Vietnam

Tropical lotus(Nelumbo) is an important and unique ecological type of lotus germplasm.Understanding the genetic relationship and diversity of the tropical lotus is necessary for its sustainable conservation and utilization.Using 42 EST-SSR(expressed sequence tag-simple sequence repeats) and 30 SRAP(sequence-related amplified polymorphism) markers,we assessed the genetic diversity and inferred the ancestry of representative tropical lotus from Thailand and Vietnam.In total,164 and 41 polymorphic bands were detected in 69 accessions by 36 EST-SSR and seven SRAP makers,respectively.Higher genetic diversity was revealed in Thai lotus than in Vietnamese lotus.A Neighbor-Joining tree of five main clusters was constructed using combined EST-SSR and SRAP markers.Cluster Ⅰ included 17 accessions of Thai lotus;cluster Ⅱ contained three Thai accessions and 11 accessions from southern Vietnam;and cluster Ⅲ was constituted by 13 accessions of seed lotus.Consistent with the results from the NeighborJoining tree,the genetic structure analysis showed that the genetic background of most Thai and Vietnamese lotus was pure,as artificial breeding has been rare in both countries.Furthermore,these analyses indicate that Thai and Vietnamese lotus germplasms belong to two different gene pools or populations.Most lotus accessions are genetically related to geographical distribution patterns in Thailand or Vietnam.Our findings showed that the origin or genetic relationships of some unidentified lotus sources can be evaluated by comparing morphological characteristics and the data of molecular markers.In addition,these findings provide reliable information for the targeted conservation of tropical lotus and parent selection in breeding novel cultivars of lotus.

Genetic diversity of the wild Asian lotus (Nelumbo nucifera) from Northern China

Asian lotus(Nelumbo nucifera Gaertn.)is an aquatic plant with ornamental,cultural,economic,and ecological values.China has abundant germplasm resources of Asian lotus.However,in many areas,the wild Asian lotuses have been destroyed and the germplasms is now facing extinction.In addition,the knowledge of the genetic diversity of the wild Asian lotus in China is poor.To identify and protect the germplasms of Chinese wild Asian lotus,eleven genomic-SSR primers,three EST-SSR primers,and three chloroplast DNA primers were used to investigate the genetic diversity among 69 samples of wild Asian lotus from 25 locations in northern China.The genetic diversity of 27 samples of wild Asian lotus from southern China and other countries,the ancient Asian lotus,Asian lotus cultivars from China,and Asian-American hybrids was also compared.The genetic diversity of the wild Asian lotus from northern China was characterized as medium,and themean values of observed heterozygosity(Ho)and expected heterozygosity(He)were 0.087 and 0.552,respectively.Based on a UPGMA dendrogram and STRUCTURE analysis,the wild Asian lotus samples in northern China were divided into three groups.The wild Asian lotus samples from northern China contained 16 haplotypes.The Nei’s genetic distance between the wild Asian lotus samples from the Songhua River basin and the Liao River basin in northeastern China was relatively small,and these germplasms might be relatively primitive compared to those from other regions.This study provides essential information regarding the genetic diversity of the wild Asian lotus resources in northern China,and provides a basis for further analysis of population-level genetic evolution through high-throughput sequencing.